The picture-in-picture feature lets you nest multiple videos in a collage and play them at the same time.
To use this feature, follow these steps:

• Add each of the videos you want to nest to a track of their own.

• Right-click one of the videos in the timeline and select "Video Event Pan/Crop".
• Scroll down with the mouse to zoom the window out.
• Drag the box around the letter "F" outward (pay attention to the preview window while doing this). Make sure the "X-Y moving tool" is set to "Move freely".

• Click the "F" to move it. Move the "F" until you find the position that works best. 

• Repeat these steps to nest additional video tracks.